SITE DIFFERENTIATION BY SYNCHROTRON-RADIATION RESONANT SCATTERING - CASE-STUDY OF BAZN2GE2

Resonance scattering was applied for the first time to the class of so lids with the AB(2)X(2) stoichiometry. A few members of this family se em to violate the developed rules describing the structure-property re lationship, and the source of ambiguity is often the experimental dete rmination of the structure itself. As an example, the newly synthesize d BaZn2Ge2 can in principle adopt either the ThCr2Si2 or the CaBe2Ge2 type structures, and conventional diffraction techniques do not allow discrimination between the two structure models. The resonance scatter ing method shows, however, that BaZn2Ge2 crystallizes in the ThCr2Si2 structure (tetragonal I4/mmm; alpha = 4.527(2) Angstrom c = 10.555(3) Angstrom, Z =; 2), in agreement with theoretical analyses.